package day3.demo4_table;

import java.util.Hashtable;
import java.util.Map;

public class Test {
    public static void main(String[] args) {
        Hashtable m = new Hashtable();
        m.put("a1",139);
        m.put("a2",133);
        m.remove("a1");
        m.get("a1");
        m.put(null,null);

    }
}
